JP7358859B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

2. Description of the Related Art Regarding techniques for forming images not intended for transfer onto a medium in image forming apparatuses such as copying machines, printers, and fax machines, the techniques described in Patent Documents 1 to 3 below are known.

Japanese Patent No. 6340927 as Patent Document 1 discloses that in order to forcibly consume toner that has been agitated and degraded without being consumed inside the developing device (14), a band-shaped toner is placed in a non-image area between toner images. Techniques for forming images are described. In the technology described in Patent Document 1, when the width of the recording medium is smaller than the maximum width dimension, the image density of the band-shaped toner image is increased, the length of the image is lengthened, and a large amount of deteriorated toner is consumed. .

Japanese Unexamined Patent Publication No. 2006-251138 as Patent Document 2 discloses that when forming a toner band outside the image forming area, the printed image is dark so that the amount of toner supplied to the cleaning device (18) is constant. It describes a technology that thins the toner band and darkens the toner band if the printed image is light.

Japanese Unexamined Patent Application Publication No. 2006-221106 as Patent Document 3 states that in a monochrome image forming mode, a toner band is formed on a photosensitive drum on which no image is formed in order to maintain the lubricity of the cleaning blade, and It describes a technique to maximize the amount of toner in the toner band of the most upstream photoreceptor drum.

Patent No. 6340927 (Claims, "0038"-"0053", FIG. 6) JP2006-251138A ("0043"-"0050", Figure 4) JP2006-221106A (Claims, "0023"-"0032", Figure 2)

The present invention ensures transferability to a medium with low transferability sensitivity compared to the case of forming an image for removing discharge products similar to a medium with high transferability sensitivity even in the case of a medium with low transferability sensitivity. At the same time, the technical challenge is to suppress the amount of developer consumed.

In order to solve the technical problem, an image forming apparatus according to the invention according to claim 1,
an image holding means that holds an image formed with a developer that is intended to be transferred to a medium and an image that is not intended to be transferred to a medium;
a transfer means for transferring an image intended for transfer to the medium to the medium;
removing means for removing an image not intended for transfer to the medium from the image holding means;
A forming means for forming an image not intended for transfer onto the medium using a developer on the image holding means before an image forming operation for forming an image intended for transfer onto the medium is started, a first forming mode for a first medium and a second forming mode for a second medium having a lower surface roughness or a higher medium density than the first medium; In the forming mode, the forming means increases the amount of developer used for forming an image not intended for transfer to the medium, compared to the second forming mode;
It is characterized by having the following.

The invention according to claim 2 provides an image forming apparatus according to claim 1 , comprising:
determining means for determining the type of medium;
It is characterized by having the following.

The invention according to claim 3 is the image forming apparatus according to claim 2 , comprising:
the discrimination means for discriminating a medium whose surface roughness is higher than a predetermined value as the first medium;
It is characterized by having the following.

The invention according to claim 4 is the image forming apparatus according to claim 2 or 3 ,
the discriminating means for discriminating a medium whose density is smaller than a predetermined value as the first medium;
It is characterized by having the following.

The invention according to claim 5 provides an image forming apparatus according to any one of claims 1 to 4 , comprising:
The first forming mode includes the forming means that increases the frequency of forming images that are not intended for transfer to the medium, compared to the second forming mode;
It is characterized by having the following.

The invention according to claim 6 provides an image forming apparatus according to any one of claims 1 to 5 , comprising:
In the case of the second medium, the density of images not intended to be transferred to the medium is set to zero.

The invention according to claim 7 provides an image forming apparatus according to any one of claims 1 to 6 , comprising:
The forming means is capable of forming an image using a plurality of color developers, and each time an image not intended for transfer to the medium is formed, the image forming means is capable of forming an image using a plurality of color developers. the forming means in which the color of the constituent developer is set;
It is characterized by having the following.

The invention according to claim 8 is the image forming apparatus according to claim 7 ,
the forming means for forming an image not intended for transfer to the medium using a developer of a color that has the smallest cumulative consumption amount among a plurality of color developers;
It is characterized by having the following.

According to the invention described in claim 1, even in the case of a medium with a small surface roughness or a medium with a high density, an image for removing discharge products similar to that of a medium with a rough surface roughness or a medium with a low density is formed. Compared to the conventional case, it is possible to suppress the amount of developer consumed while ensuring transferability to a medium with a rough surface or a medium with a low density .
According to the second aspect of the invention , it is possible to determine the type of medium and automatically switch between the first forming mode and the second mode.

According to the third aspect of the invention , the type of medium can be automatically determined based on the surface roughness.
According to the fourth aspect of the invention, the type of medium can be automatically determined based on the density of the medium.
According to the invention set forth in claim 5 , it is possible to increase the formation frequency in the first formation mode and send a large amount of developer to the removing means.

According to the sixth aspect of the invention , the amount of developer consumed can be suppressed compared to the case where the density of the image is not set to zero in the case of the second medium.
According to the invention set forth in claim 7 , compared to the case where the color of the developer is not changed, it is possible to prevent the developer of a specific color from being consumed unevenly.
According to the invention set forth in claim 8 , in an image not intended for transfer, it is possible to consume deteriorated developer compared to the case where the developer with the least amount of consumption is not used.

FIG. 1 is an overall explanatory diagram of an image forming apparatus according to a first embodiment. FIG. 2 is an enlarged explanatory diagram of the visible image forming apparatus according to the first embodiment. FIG. 3 is a block diagram showing each function provided in the control section of the image forming apparatus according to the first embodiment. FIG. 4 is an explanatory diagram of an example of the toner band of the first embodiment. FIG. 5 is an explanatory diagram of a flowchart of the toner band forming process according to the first embodiment. FIG. 6 is an explanatory diagram of voltages that act in the transfer area, FIG. 6A is an explanatory diagram of an example of low-sensitivity paper, FIG. 6B is an explanatory diagram of an example of embossed paper, and FIG. 6C is an explanatory diagram of an example of Japanese paper. Fig. 7 is an explanatory diagram of Experimental Example 1 of image quality (emboss grade) when embossed paper is used. Fig. 7A is a graph in which the number of prints is plotted on the horizontal axis and the emboss grade is plotted on the vertical axis, and Fig. 7B is a graph on the horizontal axis. This is a graph in which the adhesion force is plotted on the vertical axis and the embossing grade is plotted on the vertical axis. FIG. 8 is an explanatory diagram of an image formed in Experimental Example 1. FIG. 9 is an explanatory diagram of the experimental results of Experimental Example 2. FIG. 9A is a graph in which the horizontal axis represents the toner band density and the vertical axis represents the embossing grade, and FIG. 9B is a graph in which the horizontal axis represents the toner band density and the vertical axis represents the embossing grade. This is a graph with adhesion force on the axis. FIG. 10 is an explanatory diagram of the embossing grade results in image areas and non-image areas when the paper type and toner band density are changed.

Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to make the following explanation easier to understand, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, and the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The directions or sides indicated by Z and -Z are respectively forward, rear, right, left, upper, and lower, or front, rear, right, left, upper, and lower.
In addition, in the figures, an arrow with a ``・'' inside an ○ means an arrow pointing from the back to the front of the paper, and an ``x'' inside an ○ means an arrow pointing toward the front of the paper. It means an arrow pointing from to the back.
In addition, in the following explanation using the drawings, illustrations of members other than those necessary for the explanation are appropriately omitted for easy understanding.

FIG. 1 is an overall explanatory diagram of an image forming apparatus according to a first embodiment.
FIG. 2 is an enlarged explanatory diagram of the visible image forming apparatus according to the first embodiment.
In FIG. 1, a copying machine U as an example of an image forming apparatus includes a user interface UI as an example of an operation unit, a scanner unit U1 as an example of an image reading device, a feeder unit U2 as an example of a medium supply device, and an image recording device. It has an image forming unit U3 and a medium processing device U4 as an example of the device.

(Description of user interface UI)
The user interface UI includes input buttons UIa used for starting copying, setting the number of copies, and the like. Further, the user interface UI includes a display section UIb on which contents input using the input button UIa and the status of the copying machine U are displayed.

(Description of feeder part U2)
In FIG. 1, the feeder unit U2 includes a plurality of paper feed trays TR1, TR2, TR3, and TR4 as an example of a medium storage container. The feeder unit U2 also includes a medium supply path SH1, etc., which takes out the recording paper S, which is an example of an image recording medium, stored in each of the paper feed trays TR1 to TR4, and conveys it to the image forming unit U3. are doing.

(Description of image forming unit U3 and medium processing device U4)
In FIG. 1, the image forming section U3 includes an image recording section U3a that records an image on a recording paper S conveyed from the feeder section U2 based on a document image read by the scanner section U1.
In FIGS. 1 and 2, the drive circuit D of the latent image forming device of the image forming unit U3 sends a corresponding drive signal to each color Y at a preset time based on image information input from the scanner unit U1. ~K latent image forming devices ROSy, ROSm, ROSc, ROSk. Photosensitive drums Py, Pm, Pc, and Pk, which are examples of image carriers, are arranged below each of the latent image forming devices ROSy to ROSk.

The surfaces of the rotating photoreceptor drums Py, Pm, Pc, and Pk are uniformly charged by charging rolls CRy, CRm, CRc, and CRk, respectively, which are examples of chargers. The surfaces of the photoreceptor drums Py to Pk, whose surfaces are charged, are staticized by laser beams Ly, Lm, Lc, and Lk, which are examples of latent image writing lights output from the latent image forming devices ROSy, ROSm, ROSc, and ROSk. A latent image is formed. The electrostatic latent images on the surfaces of the photoreceptor drums Py, Pm, Pc, and Pk can be colored yellow (Y), magenta (M), cyan (C), and black (K) by the developing devices Gy, Gm, Gc, and Gk. A toner image is developed as an example of a visual image.
In the developing devices Gy to Gk, the developer consumed during development is replenished from toner cartridges Ky, Km, Kc, and Kk, which are examples of developer storage containers. The toner cartridges Ky, Km, Kc, and Kk are removably attached to the developer replenishing device U3b.

The toner images on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are transferred onto an intermediate transfer belt B as an example of an intermediate transfer member by primary transfer rolls T1y, T1m, T1c, and T1k, which are an example of a primary transfer device. The toner images are sequentially transferred in an overlapping manner in the primary transfer areas Q3y, Q3m, Q3c, and Q3k, and a color toner image as an example of a multicolor visible image is formed on the intermediate transfer belt B. The color toner image formed on the intermediate transfer belt B is conveyed to the secondary transfer area Q4.
Note that in the case of only K color image information, only the K color photosensitive drum Pk and the developing device Gk are used, and only the K color toner image is formed.
After the primary transfer, the photoreceptor drums Py, Pm, Pc, and Pk are cleaned of residual developer and paper powder adhering to their surfaces by drum cleaners CLy, CLm, CLc, and CLk, which are examples of cleaning devices for image carriers. Residues are removed.

In the first embodiment, the photoreceptor drum Pk, charging roll CRk, and drum cleaner CLk are integrated as a K-color photoreceptor unit UK, which is an example of an image carrier unit. Similarly, for other colors Y, M, and C, photoconductor units UY, UM, and UC are activated by photoconductor drums Py, Pm, and Pc, charging rolls CRy, CRm, and CRc, and drum cleaners CLy, CLm, and CLc. It is configured.
Further, the K color photoreceptor unit UK and the developing device Gk having a developing roll R0k as an example of a developer holder constitute a K color visible image forming device UK+Gk. Similarly, photoreceptor units UY, UM, UC for Y, M, and C colors and developing devices Gy, Gm, and Gc each having developing rolls R0y, R0m, and R0c are used to produce visible images for Y, M, and C colors, respectively. Image forming devices UY+Gy, UM+Gm, and UC+Gc are configured.

A belt module BM, which is an example of an intermediate transfer device, is arranged below the photoreceptor drums Py to Pk. The belt module BM includes an intermediate transfer belt B as an example of an image holding means, a drive roll Rd as an example of a drive member for the intermediate transfer body, a tension roll Rt as an example of a tension applying member, and an example of a meandering prevention member. It has a walking roll Rw, a plurality of idler rolls Rf as an example of a driven member, a backup roll T2a as an example of an opposing member, and the primary transfer rolls T1y, T1m, T1c, and T1k. Intermediate transfer belt B is supported rotatably in the direction of arrow Ya.

A secondary transfer unit Ut is arranged below the backup roll T2a. The secondary transfer unit Ut has a secondary transfer roll T2b as an example of a secondary transfer member. The area where the secondary transfer roll T2b contacts the intermediate transfer belt B forms a secondary transfer area Q4. Further, a backup roll T2a, which is an example of a facing member, is opposed to the secondary transfer roll T2b with the intermediate transfer belt B interposed therebetween. A contact roll T2c, which is an example of a power supply member, is in contact with the backup roll T2a. A secondary transfer voltage having the same polarity as the charging polarity of the toner is applied to the contact roll T2c.
The backup roll T2a, the secondary transfer roll T2b, and the contact roll T2c constitute a secondary transfer device T2 as an example of a transfer means.

A medium conveyance path SH2 is arranged below the belt module BM. The recording paper S fed from the medium supply path SH1 of the feeder unit U2 is conveyed by a conveyance roll Ra, which is an example of a medium conveyance member, to a registration roll Rr, which is an example of a conveyance timing adjusting member. The registration roll Rr conveys the recording paper S to the downstream side in time with the timing at which the toner image formed on the intermediate transfer belt B is conveyed to the secondary transfer area Q4. The recording paper S sent out by the registration roll Rr is guided by the paper guide SGr on the registration side and the pre-transfer paper guide SG1, and is conveyed to the secondary transfer area Q4.
The toner image on the intermediate transfer belt B is transferred onto the recording paper S by the secondary transfer device T2 when passing through the secondary transfer area Q4. In the case of a color toner image, the toner images that have been primarily transferred onto the surface of the intermediate transfer belt B are secondarily transferred to the recording paper S all at once.
The primary transfer rolls T1y to T1k, the secondary transfer device T2, and the intermediate transfer belt B constitute a transfer device T1y to T1k+T2+B of the first embodiment.

After the secondary transfer, the intermediate transfer belt B is cleaned by a belt cleaner CLB, which is an example of an intermediate transfer body cleaning device, and is arranged downstream of the secondary transfer area Q4. A belt cleaner CLB, which is an example of a removing unit, removes residues such as developer and paper dust that remain without being transferred from the intermediate transfer belt B in the secondary transfer area Q4.

The recording paper S onto which the toner image has been transferred is guided by a post-transfer paper guide SG2 and sent to a medium transport belt BH, which is an example of a transport member. The medium conveyance belt BH conveys the recording paper S to the fixing device F.
The fixing device F includes a heating roll Fh as an example of a heating member and a pressure roll Fp as an example of a pressure member. The recording paper S is conveyed to a fixing area Q5, which is an area where the heating roll Fh and the pressure roll Fp are in contact. When the toner image on the recording paper S passes through the fixing area Q5, it is heated and pressurized by the fixing device F and is fixed.
The visible image forming devices UY+Gy to UK+Gk, the transfer devices T1y to T1k+T2+B, and the fixing device F constitute an image recording section U3a as an example of the image forming means of the first embodiment.

On the downstream side of the fixing device F, a switching gate GT1 is provided as an example of a switching member. The switching gate GT1 selectively switches the recording paper S that has passed through the fixing area Q5 to either the ejection path SH3 or the reversing path SH4 on the side of the medium processing device U4. The recording paper S conveyed to the discharge path SH3 is conveyed to the paper conveyance path SH5 of the medium processing device U4. A curl correction member U4a, which is an example of a warpage correction member, is disposed in the paper conveyance path SH5. The curl correction member U4a corrects the warpage, so-called curl, of the recording paper S carried in. The recording paper S, whose curl has been corrected, is discharged with the image-fixed surface of the paper facing upward by a discharge roll Rh, which is an example of a medium discharge member, onto a discharge tray TH1, which is an example of a medium discharge section.

The recording paper S conveyed to the reversing path SH4 side of the image forming section U3 by the switching gate GT1 passes through a second gate GT2, which is an example of a switching member, and is conveyed to the reversing path SH4 of the image forming section U3.
At this time, if the recording paper S is to be discharged with the image-fixed surface facing downward, the transport direction of the recording paper S is reversed after the trailing edge of the recording paper S in the transport direction passes through the second gate GT2. Here, the second gate GT2 of the first embodiment is made of a thin film-like elastic member. Therefore, the second gate GT2 allows the recording paper S transported to the reversing path SH4 to pass therethrough, and when the recording paper S that has passed is reversed, or so-called switched back, it is guided to the transport paths SH3 and SH5. do. Then, the switched-back recording paper S passes through the curl correction member U4a and is discharged to the discharge tray TH1 with the image fixing surface facing downward.

A circulation path SH6 is connected to the reversing path SH4 of the image forming section U3, and a third gate GT3, which is an example of a switching member, is arranged at the connection portion. Further, the downstream end of the reversing path SH4 is connected to the reversing path SH7 of the medium processing device U4.
The recording paper S conveyed to the reversing path SH4 through the switching gate GT1 is conveyed to the reversing path SH7 side of the medium processing device U4 by the third gate GT3. The third gate GT3 of the first embodiment is made of a thin film-like elastic member, similar to the second gate GT2. Therefore, the third gate GT3 allows the recording paper S conveyed through the reversing path SH4 to pass once, and when the recording paper S that has passed is switched back, it is guided to the circulation path SH6 side.

The recording paper S transported to the circulation path SH6 is retransmitted to the secondary transfer area Q4 through the medium transport path SH2, and printing on the second side is performed.
A sheet conveyance path SH is constituted by the elements indicated by the symbols SH1 to SH7. Further, the elements indicated by the symbols SH, Ra, Rr, Rh, SGr, SG1, SG2, BH, and GT1 to GT3 constitute the sheet conveyance device SU of the first embodiment.

(Description of the control unit of Example 1)
FIG. 3 is a block diagram showing each function included in the control section of the image forming apparatus according to the first embodiment.
In FIG. 3, a control unit (controller) C, which is an example of a control means of the copying machine U, has an input/output interface I/O for inputting and outputting signals to and from the outside. Further, the control unit C has a read-only memory (ROM) in which programs, information, etc. for performing necessary processing are stored. Further, the control unit C has a RAM (random access memory) for temporarily storing necessary data. Further, the control unit C has a CPU (central processing unit) that performs processing according to a program stored in a ROM or the like. Therefore, the control unit C of the first embodiment is constituted by a small information processing device, a so-called microcomputer. Therefore, the control unit C can realize various functions by executing programs stored in the ROM or the like.

(Signal output element connected to control unit C)
The control unit C receives an output signal from a signal output element such as a user interface UI.
The user interface UI includes an input button UIa for inputting a copy start key, a numeric keypad, an arrow, etc. as an example of an input member.

(Controlled element connected to control unit C)
The control unit C is connected to the drive circuit D1 of the main drive source, the power supply circuit E, and other control elements (not shown). The control unit C outputs control signals to each circuit D1, E, etc.
D1: Drive circuit for main drive source The drive circuit D1 for main drive source rotationally drives the photosensitive drums Py to Pk, intermediate transfer belt B, etc. via a main motor M1 as an example of a main drive source.

E: Power Supply Circuit The power supply circuit E includes a power supply circuit Ea for development, a power supply circuit Eb for charging, a power supply circuit Ec for transfer, a power supply circuit Ed for fixing, and the like.
Ea: Power supply circuit for development The power supply circuit Ea for development applies a development voltage to the development rolls of the development devices Gy to Gk.
Eb: Power supply circuit for charging The power supply circuit for charging Eb applies a charging voltage for charging the surfaces of the photoreceptor drums Py to Pk to each of the charging rolls CRy to CRk.

Ec: Transfer power supply circuit The transfer power supply circuit Ec applies a transfer voltage to the primary transfer rolls T1y to T1k and the backup roll T2a.
Ed: Power supply circuit for fixing The power supply circuit Ed for fixing supplies power to the heater of the heating roll Fh of the fixing device F.

(Function of control unit C)
The control unit C has a function of executing processing according to the input signal from the signal output element and outputting a control signal to each of the control elements. That is, the control section C has the following functions.
C1: Image formation control means The image formation control means C1 drives each member of the scanner unit U1 and the image creation unit U3 in response to input to the user interface UI or input of image information from an external personal computer or the like. A job, which is an image forming operation, is executed by controlling the application timing of each voltage and the like.

C2: Drive source control means The drive source control means C2 controls the drive of the main motor M1 via the drive circuit D1 of the main drive source, and controls the drive of the photoreceptor drums Py to Pk.
C3: Power supply circuit control means The power supply circuit control means C3 controls each power supply circuit Ea to Ed to control the voltage applied to each member and the power supplied to each member.

C4: Media type storage unit The medium type storage unit C4 stores the type of recording paper S as an example of the medium used. The medium type storage unit C4 of the first embodiment stores the type of recording paper S accommodated in each of the paper feed trays TR1 to TR4 of the feeder unit U2 for each paper feed tray TR1 to TR4. In the first embodiment, the type of recording paper S accommodated in each of the paper feed trays TR1 to TR4 is stored as set and registered through input from the user interface UI. The type of recording paper S can be selected and set from "thin paper", "plain paper", "thick paper", "embossed paper", "Japanese paper", "coated paper", etc. It is also possible to set the type of recording paper S by directly inputting the paper basis weight.

C5: Medium type determining unit The medium type determining unit C5 determines the type of recording paper S used for printing. The medium type determination unit C5 of the first embodiment uses the information on the type of recording paper S of each of the paper feed trays TR1 to TR4 stored in the medium type storage unit C4 and the paper feed trays TR1 to TR4 used for printing. The type of recording paper S is determined based on TR4. Further, the medium type determining means C5 of the first embodiment may be embossed paper or Japanese paper as an example of a medium with high transferability sensitivity, or thin paper, plain paper, thick paper, or coated paper as an example of a medium with low transferability sensitivity. Determine whether it is paper.

In the specification and claims of this application, "transferability sensitivity" refers to how difficult it is for an image to be transferred to the recording paper S, and how easily it is transferred when turned over, and is dependent on temperature, humidity, etc. ``High transfer sensitivity'' means that transfer defects are likely to occur even when there are slight changes in the environment, applied voltage, conveyance speed, etc.; This is explained as "low." Therefore, thin paper, plain paper, cardboard, and coated paper with a smooth surface and a substantially uniform density of fibers such as pulp have low transfer sensitivity. On the other hand, embossed paper with an uneven surface or Japanese paper (low-density medium) with uneven density of pulp or the like and many voids inside have high transfer sensitivity. As will be described later in Figure 6, when a transfer voltage is applied to embossed paper or Japanese paper, the electrical resistance value may differ between the areas with recesses or gaps (areas without fibers) and the area with fibers. This is because if a discharge occurs in the wafer, the transfer voltage fluctuates and transfer defects are likely to occur.
In the following explanation, embossed paper and Japanese paper will be referred to as "high-sensitivity paper" as an example of the first medium, and plain paper will be referred to as "low-sensitivity paper" as an example of the second medium. It may be written.

Although the first embodiment exemplifies the case where the type of medium is determined based on the information stored in the medium type storage unit C4, the present invention is not limited to this. For example, the media thickness, light transmittance, light reflectance, polarization characteristics, surface roughness, It is also possible to install a sensor, which is an example of a detection member that detects the type of medium based on its size, to detect and determine the type of recording paper S used for printing. Therefore, for example, if the surface roughness of the recording paper S detected by the sensor is larger than a predetermined value (threshold value), that is, if the unevenness is large, it is possible to determine that it is high-sensitivity paper. . Furthermore, if the density (=weight/(thickness x area)) of the recording paper S detected by the sensor is smaller than a predetermined value (threshold), that is, if there are many voids inside the recording paper S, , it is possible to distinguish it from high-sensitivity paper.

C6: Number of printed sheets counting means The number of printed sheets counting means C6, which is an example of a means for counting the number of transfers, counts the number of printed sheets, which is an example of the number of transfers. That is, the number of printed sheets counting means C6 counts how many times a printed image, which is an example of an image to be transferred, has been transferred onto the recording paper S. In the first embodiment, when a toner band is formed as an example of an image not intended for transfer, which will be described later, the number of printed sheets is initialized, so-called reset.

C7: Developer consumption amount detection means The developer consumption amount detection means C7 detects the consumption amount of the developer used in image formation. The developer consumption detection means C7 of the first embodiment calculates the consumption amount of developer for each color based on the number of pixels written by the latent image forming devices ROSy to ROSk, and calculates the consumption amount by accumulating the results. Detect. Note that the amount of developer consumed is not limited to the case based on the number of pixels written by the latent image forming devices ROSy to ROSk, but also based on the density of the read image and the number of developing devices Gy to Gk containing the developer. It is also possible to configure it to be derived from changes in weight or the like.

FIG. 4 is an explanatory diagram of an example of the toner band of the first embodiment.
C8: Toner band formation time determination unit The toner band formation time determination unit C8 determines whether it is time to form the toner band 1, which is an example of an image not intended for transfer. In Embodiment 1, the toner band is formed at the start of a job when changing from low-sensitivity paper to high-sensitivity paper, every time in interimage area 3 during a job when high-sensitivity paper is used, and at low-sensitivity paper. A case is set in which a predetermined number of sheets of paper are printed consecutively. In other words, if low-sensitivity paper was used in a previous job and is changed to high-sensitivity paper in this job, a series of image forming operations (jobs) such as copying or printing out one or more sheets will be Before starting, a recovery mode, which is an example of an operation for forming the toner band 1, is executed. Also, during a job using high-sensitivity paper, the toner band 1 is set to be formed in an inter-image area 3, which is a non-image area between the printed images 2, which are an example of images to be transferred. There is. Furthermore, it is set so that a toner band is formed in the inter-image area 3 when 5000 sheets, as an example of a predetermined number of sheets, are successively printed on low-sensitivity paper.
In the first embodiment, the case where the toner band 1 is formed every time in the inter-image area 3 in the case of high-sensitivity paper is illustrated, but the toner band 1 is formed once every two times in the inter-image area 3. It is also possible to form the band 1 or to form the toner band 1 once every three or more times.

C9: Color determining unit The color determining unit C9 determines the color forming the toner band 1. The color determining unit C9 of the first embodiment determines the color for forming the toner band 1 during a high-sensitivity paper job or during printing on low-sensitivity paper, which is an example of the time when the toner band is formed. . That is, each time the toner band 1 is formed, the color of the toner band 1 is determined. Further, the color determining means C9 of the first embodiment selects the color with the least amount of developer consumption from the toner band based on the amount of developer consumption of each color detected by the developer consumption amount detecting means C7. 1 is determined as the color forming the color. Note that the present invention is not limited to this, and it is also possible to use two or three colors in descending order of consumption among the four colors Y, M, C, and K. Note that the present invention is not limited to the case where the amount of developer consumed is small, and any parameter related to developer deterioration can be used. For example, parameters such as when the developing devices Gy to Gk operate for more than a certain period of time and the developer is stirred while the consumption amount is below a predetermined threshold, or when the amount of developer supplied to the developing devices Gy to Gk is small. It is also possible to use

C10: Toner band forming means The toner band forming means C10 forms a toner band 1 as an example of an image for supplying developer to a cleaning means. In the recovery mode as an example of the first formation mode, the toner band forming means C10 of the first embodiment forms Y, M, Y, M, An image with a density of 10% for each color of C and K, that is, an image with a total density of 40%, is formed equivalent to 100 A4 pages = equivalent to 10 A4 solid pages, and in the secondary transfer area Q4, the secondary transfer voltage is reversed. A polar voltage is applied to supply the developer of the toner band 1 to the belt cleaner CLB.
Further, in the toner band forming means C10 of the first embodiment, during a high-sensitivity paper job, a high-sensitivity paper mode as an example of the first formation mode is executed, and the color determined by the color determination means C9 is executed. , a toner band 1 is formed for each interimage area 3. Furthermore, when printing on low-sensitivity paper, the toner band forming means C10 executes the low-sensitivity paper mode as an example of the second formation mode, and prints every 5000 pages in the color determined by the color determination means C9. Next, a toner band 1 is formed in the interimage area 3.

Note that the density of toner band 1 for every 5000 pages when printing low-sensitivity paper is lower than that of toner band 1 when printing high-sensitivity paper. That is, the amount of developer used is reduced. As an example, the density of toner band 1 for high-sensitivity paper can be set to 0.75%, and the density of toner band 1 for low-sensitivity paper can be set to 0.25%. Note that the density of the toner band 1 in the case of high-sensitivity paper is preferably 0.5% or more, and more preferably 0.75% or more. In addition, although the density of toner band 1 of low-sensitivity paper is 0.25%, the density is not limited to this, and the density of toner band 1 of low-sensitivity paper may be 0%, that is, a configuration in which toner band 1 is not formed in the case of low-sensitivity paper. It is also possible to do so. By not forming the toner band 1 in the case of low-sensitivity paper, it is possible to further suppress the amount of developer consumed as a whole. Note that in the specification and claims of this application, the density of the toner band 1 in the case of low-sensitivity paper is used to include the case of 0%.
Note that even if the density of toner band 1 on low-sensitivity paper and toner band 1 on high-sensitivity paper is the same, toner band 1 is formed more frequently on high-sensitivity paper, and is used less as a whole. The amount of developer used for high-speed paper is greater.

Further, in the first embodiment, the size of the toner band 1, that is, the length L0 and width of the intermediate transfer belt B in the conveyance direction are set to predetermined sizes. As an example, the width L1 is set to a width corresponding to the maximum width of the print image 2a that can be formed by the copying machine U (for example, A3). Therefore, the width is set to cover the entire range of the minimum print image width (for example, A5). Note that the width L1 can also be set to a length that exceeds the width of the maximum printed image 2a and is less than or equal to the width of the intermediate transfer belt B.
Note that the longer the length L0 and width L1 of the intermediate transfer belt B in the conveying direction, the more the amount of developer used increases. Therefore, in Example 1, the density is increased in the case of high-sensitivity paper, but it is also possible to increase the width L1 or the length L0 without increasing the density, or to increase the length L0 while increasing the density. It is also possible to make the length longer.

(Explanation of flowchart of Example 1)
Next, the flow of control in the copying machine U of the first embodiment will be explained using a flowchart.
(Explanation of flowchart of toner band formation process)
FIG. 5 is an explanatory diagram of a flowchart of the toner band forming process according to the first embodiment.
The processing of each step ST in the flowchart of FIG. 5 is performed according to a program stored in the control unit C of the copying machine U. Further, this process is executed in parallel with various other processes of the copying machine U. Therefore, the process of forming an image on each recording paper S with the start of a job is executed in parallel with the flowchart of FIG.
The flowchart shown in FIG. 5 is started when the copying machine U is powered on.

In ST1 of FIG. 5, it is determined whether a job has been started. If yes (Y), proceed to ST2; if no (N), repeat ST1.
In ST2, it is determined whether the type of recording paper S has been changed from low-sensitivity paper to high-sensitivity paper. If yes (Y), proceed to ST3; if no (N), proceed to ST4.
In ST3, before the print image 2 is formed, the recovery mode is executed. That is, in the recovery mode, images with a density of 40% are formed for 100 A4 pages. Then, proceed to ST5.
In ST4, it is determined whether the recording paper S of the job to be started is high-sensitivity paper. If yes (Y), proceed to ST5; if no (N), proceed to ST7.
In ST5, formation of the print image 2 is started, and a high-density toner band 1 for high-sensitivity paper is formed in the interimage area 3. Then, proceed to ST6.
In ST6, it is determined whether the job has ended. If yes (Y), return to ST1; if no (N), repeat ST6.

In ST7, formation of the print image 2 is started, and counting of the number of printed sheets is started. Then, proceed to ST8.
In ST8, it is determined whether it is time to form a toner band. That is, it is determined whether the counted number of printed sheets has reached 5000 sheets, which is a threshold value for determination. If yes (Y), proceed to ST9; if no (N), proceed to ST10.
In ST9, the following processes (1) and (2) are executed, and the process proceeds to ST10.
(1) Form a low-density toner band 1 for low-sensitivity paper.
(2) Reset the number of prints. That is, initialize it.
In ST10, it is determined whether the job has ended. If yes (Y), return to ST1; if no (N), return to ST7.

(Effect of Example 1)
In the copying machine U of Embodiment 1 having the above configuration, the printed image 2 is secondarily transferred from the intermediate transfer belt B to the recording paper S in accordance with the image forming operation. At this time, discharge occurs locally in the secondary transfer area Q4, and discharge products adhere to the intermediate transfer belt B. The discharge products are removed by the belt cleaner CLB, but some of the discharge products are not completely removed and remain on the intermediate transfer belt B, and the number of discharge products increases over time. As a result, the adhesion force between the intermediate transfer belt B and the developer of the primary transferred printed image 2 becomes high. When this adhesion force increases, it becomes difficult for the developer to be transferred to the recording paper S during secondary transfer. Therefore, transfer defects are more likely to occur, and image quality defects are more likely to occur.

In order to cope with the increase in discharge products over time, it has been conventionally practiced to form images that are not intended for transfer, such as toner bands. The developer is externally added with a lubricant or the like as an external additive, and the developer is supplied to the belt cleaner CLB to improve the cleaning ability of the belt cleaner CLB and remove discharge products that could not be removed completely. things are being done.

FIG. 6 is an explanatory diagram of voltages that act in the transfer area, FIG. 6A is an explanatory diagram of an example of low-sensitivity paper, FIG. 6B is an explanatory diagram of an example of embossed paper, and FIG. 6C is an explanatory diagram of an example of Japanese paper.
In FIG. 6, since the low-sensitivity paper S1 such as plain paper has a smooth surface and almost no voids inside, the secondary transfer voltage V1 acts almost uniformly on the secondary transfer area Q4.
On the other hand, as shown in FIG. 6B, the embossed paper S2, which is an example of high-sensitivity paper, has unevenness on its surface, and a gap 12 is formed between it and the intermediate transfer belt B at the concave portion S2a. Therefore, the electrical resistance value in the thickness direction changes between the convex portion S2b without the gap 12 and the concave portion S2a with the gap 12. Therefore, discharge is likely to occur in the gap 12, and the secondary transfer voltage V1a acting on the recess S2a may change. Therefore, in the recessed portion S2a, transfer defects are more likely to occur than in the low-sensitivity paper S1.
In FIG. 6C, in Japanese paper S3, which is an example of high-sensitivity paper, voids (gaps) 13 are more likely to occur inside, and the portions with voids 13 are more similar to the case of embossed paper S2 than the portions without voids 13. transfer defects are more likely to occur. That is, not only Japanese paper but also low-density recording paper S with internal voids is likely to cause transfer defects.

Therefore, if the high-sensitivity papers S2 and S3 are used in a situation where transfer defects are likely to occur due to an increase in discharge products over time, there is a problem in that transfer defects are even more likely to occur. Therefore, the high-sensitivity papers S2 and S3 are more susceptible to discharge products (higher sensitivity) than the low-sensitivity paper S1.
On the other hand, in Example 1, when high-sensitivity papers S2 and S3 are used, the amount of developer used in toner band 1 is increased compared to when low-sensitivity paper S1 is used. ing. That is, compared to the case of the low-sensitivity paper S1, the removal performance of discharge products is improved, and the amount of discharge products on the intermediate transfer belt B is reduced. Therefore, compared to the conventional case where a constant toner band is formed regardless of paper type, when high-sensitivity papers S2 and S3 are used, the adverse effects of discharge products are reduced and transfer defects are less likely to occur. .

In particular, in the first embodiment, when the recording paper S is changed from low-sensitivity paper S1 to high-sensitivity paper S2, S3, a recovery mode for removing discharge products on intermediate transfer belt B is executed. Therefore, compared to the case where the recovery mode is not executed, printing of the print image 2 is executed with fewer discharge products on the surface of the intermediate transfer belt B, and the occurrence of transfer defects to the high-sensitivity papers S2 and S3 is reduced. be done.
Furthermore, while a job is being executed on the high-sensitivity papers S2 and S3, a toner band 1 is formed for each interimage area 3. Therefore, compared to the case where toner band 1 is not formed, the cleaning ability of belt cleaner CLB is maintained in a high state, and discharge products on the surface of intermediate transfer belt B are easily removed continuously during job execution. That is, the amount of discharge products on the surface of the intermediate transfer belt B is easily maintained in a state of being small. Therefore, occurrence of transfer defects due to discharge products accumulated during job execution is reduced.
Furthermore, on the low-sensitivity paper S1 where transfer defects are less likely to occur, a low-density toner band 1 is formed periodically (every 5000 sheets). Therefore, the discharge products are removed periodically to suppress the occurrence of transfer defects, and the amount of toner consumed is suppressed compared to the case where a high-density toner band is formed.

Further, in the first embodiment, in the high-sensitivity paper mode and the low-sensitivity paper mode, the color of the developer used is set to the developer with the least amount of consumption. The developer whose consumption amount is small increases the rate at which it deteriorates due to stirring within the developing devices Gy to Gk. Therefore, by forcibly using the deteriorated developer as the toner band 1, the deteriorated developer is easily replaced. When the developer is replaced and the proportion of deteriorated developer is reduced, development defects and transfer defects are also reduced.

(Experiment example)
Fig. 7 is an explanatory diagram of Experimental Example 1 of image quality (emboss grade) when embossed paper is used. Fig. 7A is a graph in which the number of prints is plotted on the horizontal axis and the emboss grade is plotted on the vertical axis, and Fig. 7B is a graph on the horizontal axis. This is a graph in which the adhesion force is plotted on the vertical axis and the embossing grade is plotted on the vertical axis.
Next, an experiment was conducted to confirm the effects of the present invention.
(Experiment example 1)
In Experimental Example 1, an experiment was conducted to see how the image quality (emboss grade) changes when continuous printing is performed on embossed paper without forming a toner band. In the experiment, Lezac 66 manufactured by Tokushu Tokai Paper Co., Ltd. was used as the embossed paper. The black LEZAC 66 is referred to as ``LEZAC K'', and the blue LEZAC 66 is referred to as ``LEZAC B''. Additionally, Versant 3100 Press manufactured by Fuji Xerox Co., Ltd. was used as an image forming apparatus. In the experiment, the entire black surface (density 100 %) and a 60% density halftone image, and a blue full-surface solid (density 100%) and a 60% density halftone image to determine the emboss grade and the adhesion of the developer at that time to the intermediate transfer belt B. was measured.
To measure the adhesion force, stop the intermediate transfer belt B while the developer is attached to the intermediate transfer belt B, blow air onto the developer, and visually check the pressure of the air when the developer is blown off. The average adhesion force (nN) per developer was calculated.
For the emboss grade, roughness of the image was visually observed. Note that an emboss grade of 3 or less is considered an acceptable range.

FIG. 8 is an explanatory diagram of an image formed in Experimental Example 1.
Further, in Experimental Example 1, as shown in FIG. 8, three image areas 21 arranged at intervals and a non-image area 22 between the image areas 21 were formed as images. That is, in the width direction of the intermediate transfer belt B, the developer is supplied to the belt cleaner CLB in the area corresponding to the image area 21, but the developer is supplied to the belt cleaner CLB in the area corresponding to the non-image area 22. The situation is that it is not possible.

In FIG. 7A, it was confirmed that in a situation where no toner band was formed, the embossing grade decreased over time in the portion corresponding to the non-image area 22. That is, in areas such as the image area 21 where developer is continuously supplied, it is possible to print at an acceptable grade on embossed paper, but in areas such as the non-image area 22 where developer is not supplied. It was confirmed that the image quality deteriorated.
In FIG. 7B, although there are variations, it has been confirmed that, as a trend, when continuous printing is performed in the non-image area 22, the adhesion of the developer on the intermediate transfer belt B increases, and the embossing grade deteriorates. It was also confirmed that when the adhesion force was at least lower than 30 [nN], the embossing grade fell within the permissible range.

(Experiment example 2)
FIG. 9 is an explanatory diagram of the experimental results of Experimental Example 2. FIG. 9A is a graph in which the horizontal axis represents the toner band density and the vertical axis represents the embossing grade, and FIG. 9B is a graph in which the horizontal axis represents the toner band density and the vertical axis represents the embossing grade. This is a graph with adhesion force on the axis.
In Experimental Example 2, the relationship between the concentration of toner band 1 and the embossing grade and adhesion force was observed. In Experimental Example 2, an experiment was conducted under the same experimental conditions as in Experimental Example 1.
In FIG. 9, when the density of toner band 1 is "0%", that is, when 5,000 sheets are printed without forming toner band 1, as shown in the upper row of "0%" in the graph of FIG. The embossing grade was poor at "4", and the adhesion was also 32 "nN". If you run the recovery mode from this state, the emboss grade will recover to ``3'' as shown below ``0%'' in the graph, and the adhesion force will also be about 29.7 [nN]. has recovered.
Also, when 5000 sheets were printed with the density of toner band 1 at "0.5%", it was better than when it was "0%", and when the density of toner band 1 was "0.75%" or higher, the embossing grade stabilized at 3 or less. However, it was confirmed that the adhesive force was also stable at 30 "nN" or less. Therefore, in the case of embossed paper, it was confirmed that the toner band content is preferably 0.5% or more, and particularly preferably 0.75% or more.

FIG. 10 is an explanatory diagram of the embossing grade results in image areas and non-image areas when the paper type and toner band density are changed.
As shown in Figure 10, J paper (plain paper) and OSC paper (coated paper) manufactured by Fuji Xerox Co., Ltd. are examples of low-sensitivity paper, Rendezvous (rough paper) of Korean paper is an example of high-sensitivity paper, The experiment was conducted using Rezac (embossed paper) and Boss Yuki (embossed paper) manufactured by Tokushu Tokai Paper Co., Ltd. Note that "Lezac" is the same as in Experimental Example 1.
From the results shown in FIG. 10, no transfer failure was observed in the image area 21 or non-image area 22 with low-sensitivity paper. In other words, it was confirmed that toner band 1 had few problems even at a low density (0%). On the other hand, with high-sensitivity paper, it was confirmed that when the toner band 1 has a low density, the image quality deteriorates in the non-image area, and the higher the density of the toner band 1, the better the image quality.
In the experimental example shown in FIG. 10, an experiment was also conducted to see if the results were different between black toner band 1 and blue toner band 1, but as a result, no difference was observed in the embossing grade depending on the developer color.

(Example of change)
Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various changes can be made within the scope of the gist of the present invention as described in the claims. is possible. Modifications (H01) to (H08) of the present invention are illustrated below.
(H01) In the above embodiment, a copying machine U was illustrated as an example of an image forming apparatus, but the invention is not limited to this, and it may be applied to a FAX, or may have multiple functions such as a FAX, a printer, a copying machine, etc. It is applicable to multifunction devices, etc. Further, the image forming apparatus is not limited to a multi-color developing image forming apparatus, but can also be constructed using a single color, so-called monochrome image forming apparatus.
(H02) In the above embodiments, the specific numerical values illustrated can be changed as appropriate according to changes in design and specifications.

(H03) In the above embodiment, the toner band 1 is formed for every intermediate image area 3 for high-sensitivity paper, that is, for every print image 2, and for low-sensitivity paper, the toner band 1 is formed for every 5000 sheets. It is not limited to this. It is desirable to form toner band 1 frequently for high-sensitivity paper, and toner band 1 infrequently for low-sensitivity paper, but if toner consumption is acceptable, even low-sensitivity paper can be used for high-sensitivity paper. It is also possible to use the same frequency as paper. However, in this case, in the case of high-sensitivity paper, the density of the toner band 1 needs to be higher than that in the case of low-sensitivity paper.
Further, although the frequency of forming the toner band is exemplified as every one sheet or every 5,000 sheets, it is not limited to this and may be variable. For example, in response to the deterioration of the intermediate transfer belt B over time, the number of times the intermediate transfer belt B is used (cumulative number of sheets printed from a new state) increases, and the intermediate transfer belt B deteriorates over time. It is also possible to change the correction performed every 5000 sheets to every 4000 sheets in response to the increase in the number of sheets.

(H04) In the embodiments described above, it is desirable to execute the recovery mode, but it is also possible to adopt a configuration in which the recovery mode is not executed. Furthermore, in the case of low-sensitivity paper, the toner band 1 is formed once every 5,000 sheets, but it is also possible to perform the recovery mode once every 5,000 sheets, for example.
In addition, in recovery mode, depending on how long low-sensitivity paper was used continuously before switching to high-sensitivity paper, the density and area of the toner band formed in recovery mode (A4, 100 pages) It is also possible to adopt a configuration that adjusts the amount (equivalent). That is, during the period when low-sensitivity paper is used, toner band 1 is formed only infrequently, and when low-sensitivity paper is used for a long period of time, many discharge products accumulate on intermediate transfer belt B. There is a possibility that it is. Therefore, the more sheets of low-sensitivity paper are printed before switching to high-sensitivity paper, the higher the density or the larger area of toner band 1 can be made. It is also possible to reduce the concentration of 1 or reduce the area.

(H05) In the above embodiment, the case where the color of the toner band 1 is set to a color with a low consumption amount is illustrated, but the present invention is not limited to this. It is possible to fix the color to a specific color, or it is also possible to provide a separate developer dedicated to the toner band in addition to the four colors. In addition, it is also possible to use two or three specific colors, or to always form the toner band 1 using all four colors.
(H06) In the embodiment described above, it is desirable that the recovery mode is executed before starting a job, but it is also possible to execute the recovery mode every time a job ends. Furthermore, when high-sensitivity paper is printed continuously, it is also possible to temporarily stop printing and execute the recovery mode every predetermined number of sheets (for example, 500 sheets).

(H07) In the above embodiment, the belt-shaped toner band 1 was illustrated as an example of an image not intended for transfer, but the invention is not limited to this. The shape, size, number, etc. can be changed depending on the design, specifications, etc. That is, it is possible to make it into a polygonal or circular figure or a letter instead of a band shape, and the size and number can also be changed. Further, instead of changing the density, it is also possible to increase the amount of developer used by increasing the size, thereby increasing the amount of developer sent to the belt cleaner CLB.
(H08) In the above example, increasing the amount of developer used in order to suppress transfer defects in the case of high-sensitivity paper was illustrated. Alternatively, it is also possible to improve the ability to remove discharge products to make it easier to transfer the developer, thereby suppressing transfer defects. That is, when printing on high-sensitivity paper, it is also possible to configure an operation mode that suppresses adhesion more than when printing on low-sensitivity paper. Note that this operation mode can be executed instead of each forming mode of the embodiment, or in addition to each forming mode. Specifically, as an example of improving the ability to remove discharge products from the image holding means, it is possible to increase at least one of the area, density, and frequency of the toner band 1. As another example, increasing the number of rotations of the rotating brush in the belt cleaner (cleaning means) or increasing the contact pressure may be considered.

1...Image not intended for transfer to a medium,
2...Image intended for transfer to a medium,
B...image holding means,
C5...discrimination means,
C10...forming means,
CLB...removal means,
S, S1, S2, S3...medium,
S1...second medium,
S2, S3...first medium,
T2...transfer means,
U...Image forming device.

Claims (8)

an image holding means that holds an image formed with a developer that is intended to be transferred to a medium and an image that is not intended to be transferred to a medium;
a transfer means for transferring an image intended for transfer to the medium to the medium;
removing means for removing an image not intended for transfer to the medium from the image holding means;
A forming means for forming an image not intended for transfer onto the medium using a developer on the image holding means before an image forming operation for forming an image intended for transfer onto the medium is started, a first forming mode for a first medium and a second forming mode for a second medium having a lower surface roughness or a higher medium density than the first medium; In the forming mode, the forming means increases the amount of developer used for forming an image not intended for transfer to the medium, compared to the second forming mode;
An image forming apparatus comprising: determining means for determining the type of medium;
The image forming apparatus according to claim 1, further comprising: the discrimination means for discriminating a medium whose surface roughness is higher than a predetermined value as the first medium;
The image forming apparatus according to claim 2, further comprising: the discriminating means for discriminating a medium whose density is smaller than a predetermined value as the first medium;
The image forming apparatus according to claim 2 or 3, further comprising: The first forming mode includes the forming means that increases the frequency of forming images that are not intended for transfer to the medium, compared to the second forming mode;
The image forming apparatus according to any one of claims 1 to 4 , further comprising: 6. The image forming apparatus according to claim 1, wherein, in the case of the second medium, the density of an image not intended to be transferred to the medium is set to zero . The forming means is capable of forming an image using a plurality of color developers, and each time an image not intended for transfer to the medium is formed, the image forming means is capable of forming an image using a plurality of color developers. the forming means in which the color of the constituent developer is determined;
7. The image forming apparatus according to claim 1, further comprising: an image forming apparatus comprising: an image forming apparatus; the forming means for forming an image not intended for transfer to the medium using a developer of a color that has the smallest cumulative consumption amount among a plurality of color developers;
The image forming apparatus according to claim 7 , further comprising:

Images